An enhanced volume control menu available in the new test build of Windows 11 Preview Build 25309, allows you to adjust the volume of each application separately, as well as choose a playback device and activate the surround sound function.
You can open the updated volume mixer by clicking on the corresponding button in the quick settings menu or by using the Win + Ctrl + V key combination.
There is no word yet on when the mixer will appear in the stable version of Windows 11. Microsoft notes that it is not even yet available to all users using test builds from the Dev Channel. But better late than never.